Impact of distribution of carotid intraplaque neovessels on plaque vulnerability.

BACKGROUND AND PURPOSE: Intraplaque neovessels (INVs) are considered important contributors to carotid plaque vulnerability. The purpose of this study was to examine whether differences in INV distribution affect plaque vulnerability. METHODS: The study cohort comprised 110 patients with significant stenosis of the carotid artery who had undergone carotid endarterectomy. The distribution of INVs within carotid plaques was assessed by immunohistochemical studies using anti-CD-34 antibody as a marker for endothelial cells. First, we divided the patients into M group and S group depending on the numbers of INVs in middle and shoulder region. Next, we categorized carotid plaques into four categories according to the distributions of INVs: Shoulder, Middle, Mixed, and Scarce. We then compared total area of intraplaque hemorrhage, cholesterol, and calcification, width of thinnest fibrous cap, and number of INVs between the four categories of plaque. RESULTS: The area of intraplaque hemorrhage was significantly larger in the M group than in the S group (P=0.011). Meanwhile, symptomatic carotid stenosis was significantly more frequently associated with the Middle and Mixed than the Shoulder and Scarce categories (P<0.01). The area of intraplaque hemorrhage was significantly different between the four groups (P=0.022). Rupture of the fibrous cap was more frequently detected in the Middle and Mixed than the other categories (P=0.002). CONCLUSIONS: INVs in the middle region of carotid plaques are strongly associated with symptomatic carotid stenosis, intraplaque hemorrhage, and rupture of the fibrous cap. Our findings indicate that the distribution of INVs may affect plaque vulnerability.

Multiple Thrombi in the Heart in Trousseau Syndrome Caused by Pancreatic Carcinoma.

A 65-year-old woman presented to our emergency room because of sudden onset of right hemiparesis with severe fatigue. Neurological examination revealed right hemiparesis with right facial numbness and an extensor planter response on the right side.Magnetic resonance imaging with diffusion-weighted imaging revealed multiple highintensity areas in both cerebral hemispheres and the right cerebellum. A diagnosis of acute stage of multiple brain infarctions caused by emboli was made. An abdominal computed tomography showed a pancreatic tumor with multiple liver metastases. High D-dimer and serum carbohydrate antigen 19-9 concentration strongly suggested Trousseau syndrome associated with pancreatic cancer. The patient had another large embolic stroke and died on day 47. Autopsy was performed. There were large thrombi in the left ventricular apex and in the left atrial appendage There was also a papillary-shaped vegetation on the aortic valve that consisted mainly of fibrin without any inflammatory cells or destruction of the valve, these findings being characteristic of NBTE. This case is remarkable in that the patient had 3 different types of cardiac thrombi in her heart associated with Trousseau syndrome.

Guillain-Barré and Miller Fisher syndromes in patients with anti-hepatitis E virus antibody: a hospital-based survey in Japan.

There have been reports from several countries that hepatitis E virus (HEV) infection is frequently associated with Guillain-Barré syndrome (GBS). This study aimed to determine the frequency of HEV infection associated with GBS in Japanese patients, and to clarify the clinical characteristics of these patients. Sera obtained from 63 patients with GBS or Miller Fisher syndrome (MFS) and 60 control subjects were examined for both HEV-IgM and HEV-IgG. Of the 63 patients, three were positive for both HEV-IgM and elevated hepatic enzymes: Two had GBS, and one had MFS. No control subjects were positive for HEV-IgM. Our study demonstrated that 4.8 % of patients with GBS or MFS from our institution had associated acute HEV infection. There were no clinical differences between GBS with HEV infection and other GBS cases. To our knowledge, this is the first survey in Japan of HEV-associated GBS or MFS.

Impact of insufficient drug efficacy of antiparkinson agents on patient's quality of life: a cross-sectional study.

BACKGROUND: To understand the current state of insufficient drug efficacy experienced by patients with Parkinson's disease (PD) and its effects on quality of life (QOL), we conducted a survey of patients with PD and analyzed the results from 2,630 completed questionnaires. METHODS: The questionnaires inquired about age, sex, Hoehn and Yahr stage, disease duration, drugs currently being taken, and the current state of insufficient drug efficacy; it also included items of the Parkinson's Disease Questionnaire-8 (PDQ-8). Questionnaires were mailed to members of the Japan Parkinson's Disease Association. RESULTS: Approximately 70% of all subjects reported some type of insufficient drug efficacy, and around half of these experienced this early in the morning or at night. The proportion of subjects who experienced insufficient drug efficacy was found to increase with greater disease severity according to the Hoehn and Yahr stage. However, even among patients with stage I severity, insufficient drug efficacy was reported by approximately 40% of the respondents. QOL was significantly lower in patients who experienced insufficient drug efficacy than in those who did not (PDQ-8 summary index; 42.0 ± 20.1 vs. 30.0 ± 19.5; p < 0.0001). CONCLUSIONS: These results suggest that insufficient drug efficacy might affect the quality of life of patients in most stages PD including the early stages. Therefore, greater awareness of insufficient drug efficacy gained by questioning patients might help medical practitioners in taking appropriate actions.

Efficacy and Safety of a New Delivery Assist Catheter with a Flexible, Spindle-Shaped Shaft in Mechanical Thrombectomy.

OBJECTIVE: Large-bore aspiration catheters (ACs) are used successfully in mechanical thrombectomy (MT). However, tortuous access routes prevent device navigation because of the ledge effect. The AXS Offset Delivery Assist Catheter is designed to reduce the ledge effect. The purpose of this study was to evaluate whether the Offset affects AC navigation compared with standard inner microcatheters in MT. METHODS: We retrospectively investigated 75 MTs for anterior circulation occlusion between January 2018 and May 2022 at our hospital. All MTs were performed using an AC, and 2 types of inner microcatheter (Offset or 0.021-0.027-inch standard microcatheter) were chosen randomly during AC navigation. The patients' characteristics, MT techniques, angiographic findings, and clinical outcomes were compared between the Offset and standard group (Non-Offset). The puncture to first pass of the lesion time was investigated to compare the characteristics of the inner catheters. RESULTS: The Offset group comprised 12 patients versus 63 in the Non-Offset group. Although most baseline clinical characteristics and outcomes were similar between the groups, the puncture to first pass of the lesion time was significantly shorter in the Offset versus Non-Offset group (31 ± 10 vs. 46 ± 24 minutes, respectively; P = 0.032). In the Offset group, all stent retrievers were deployed via the Offset. One artery dissection and 8 symptomatic intracranial hemorrhages occurred in the Non-Offset group; no complications occurred in the Offset group. CONCLUSIONS: The AXS Offset delivery assist catheter permitted faster and safer navigation of various ACs to the occlusions compared with standard delivery microcatheters in MT.

Analysis of Cerebrovascular Events after Coil Embolization of Unruptured Cerebral Aneurysms in Patients Taking Anticoagulants.

Objective: Antiplatelet therapy is advised to prevent thrombotic complications during endovascular coil embolization of unruptured cerebral aneurysms. Due to multiple antithrombotic treatments, bleeding risk is a concern in patients using oral anticoagulants for existing comorbidities. We investigated the hemorrhagic and ischemic events following endovascular treatment (EVT) of unruptured cerebral aneurysms in patients taking anticoagulation and antiplatelet therapy. Methods: Between March 2013 and February 2019, 262 patients undergoing EVT for unruptured cerebral aneurysms and having at least 6 months of postoperative follow-up data were included in this retrospective study. Patients taking oral anticoagulants and antiplatelet drugs for cerebral vascular events following EVT were compared with those taking only antiplatelet agents. Results: Of the 262 patients, 12 (4.6%) used anticoagulants before EVT for a preexisting condition. Cerebrovascular events after coil embolization were observed in 3 patients taking both anticoagulant and antiplatelet drugs and in 14 patients taking only antiplatelet drugs (25% vs. 5.6%, respectively, p = 0.035). Vitamin K antagonist (VKA) was administered in five patients and direct oral anticoagulants (DOACs) in seven patients. Patients taking VKA experienced cerebrovascular events, whereas those taking DOACs did not (p = 0.045). Conclusion: Our study showed that patients using oral anticoagulants and antiplatelet drugs experienced more cerebrovascular events after EVT for unruptured cerebral aneurysms. These results suggest that in patients requiring oral anticoagulants, DOACs may be more beneficial than VKA for preventing stroke occurrences after EVT.

HTLV-1-associated demyelinating neuropathy: A case report and review of the literature.

A 78-year-old man developed paresthesias in the extremities. He was referred to our hospital because of positive anti-human T-cell leukemia virus type 1 (HTLV-1) antibodies in the serum and the presence of abnormal lymphocytes. He was diagnosed as chronic-type adult T-cell leukemia/lymphoma. Neurological examination revealed sensory impairment in the distal parts of the extremities with loss of deep tendon reflexes. Nerve conduction study showed motor and sensory demyelinating polyneuropathy, indicating a diagnosis of HTLV-1-associated demyelinating neuropathy. Corticosteroid therapy followed by intravenous immunoglobulin therapy improved his symptoms. Since demyelinating neuropathy associated with HTLV-1 infection is not well recognized, we here report its characteristics and clinical course through our case report and literature review.

[Carotid artery stenting using cerebral angiography 3D fusion imaging without contrast agent: a case report].

A 79-year-old-man with a clinical history of type 2 diabetes and hypertension was admitted to our hospital for recurrent right hemiparesis. He was referred to our department with left internal carotid artery stenosis. Cerebral angiography with a slight contrast agent revealed NASCET 86% stenosis at the left internal carotid bifurcation. Although no neurological deficit was observed, he had a renal dysfunction with an estimated glomerular filtration rate of 32.2 ml/min/1.73 m2. We used a 3D fusion image obtained from the initial angiography with B-mode and intravascular ultrasound to avoid aggravating renal function instead of using a contrast medium. Following the procedure, favorable expansion of the stenotic region was achieved, and no evidence of recurrence was seen during the follow-up period. 3D fusion imaging is a valuable and safe method for endovascular treatment of carotid artery stenosis for patients with renal dysfunction.

[Recurrent syncope due to sick sinus syndrome in a patient with myasthenia gravis associated with thymoma].

We report a 51-year-old man who was admitted to our hospital due to repeated episodes of syncope associated with generalized myasthenic symptoms. Due to myasthenic symptoms with the presence of anti-AchR antoantibody, he was diagnosed as myasthenia gravis (MG) associated with thymoma. However, Holter ECG showed long pause with maximum R-R interval of 3.8 seconds and paroxysmal atrial fibrillation, indicating the diagnosis of sick sinus syndrome. After pace maker implantation and combination therapy with thymomectomy and steroid administration, no arrhythmia in repeated Holter ECG was found. In addition, an anti-kv1.4 antibody was positive in our case. The involvement of cardiomyopathy in patients with MG has been reported, including the association with sudden death. The anti-kv1.4 antibody was recently identified in cases of myasthenia gravis associated with cardiomyositis. After treatments, no arrhythmia was found in our case. Although the cardiomyopathy was not diagnosed in our case because of lacking of histological confirmation, clinical course associated with positive anti-kv1.4 antibody suggested that the cause of syncope might be immune-related cardiomyopathy. To prevent fatal complication of arrhythmia, appropriate examination and therapy against cardiomyopathy associated with myasthenia gravis should be considered.

[A Case of Paraneoplastic Opsoclonus and Ataxia Appeared at Progression of Prostate Cancer].

An 80-year-old man was diagnosed with prostate cancer in April 2014 and underwent anticancer treatment. His serum prostate-specific antigen (PSA) level was abruptly increased on December 26, 2014. He was admitted to the neurological department of our hospital on January 14, 2015, because of the appearance of staggering gait and diplopia. Neurological examination revealed marked opsoclonus, limb ataxia and ataxic gait. The patient was diagnosed with paraneoplastic opsoclonus and ataxia caused by prostate cancer relapse. Steroid pulse therapy was initiated and his symptoms, including opsoclonus and ataxia, markedly improved. Although most cases of paraneoplastic opsoclonus precede the discovery of cancer, our case developed symptoms simultaneously with relapse and acute progression of prostate cancer. Paraneoplastic opsoclonus with prostate cancer is rare. Additionally, our case showed excellent response of opsoclonus to steroid therapy without treatment of the underlying disease. (Received June 1, 2020; Accepted September 18, 2020; Published February 1, 2021).

[A Case of Immune-Mediated Necrotizing Myopathy Associated with Primary Sjögren Syndrome].

A 66-year-old woman visited our hospital complaining of shortness of breath during exertion and progressive weakness in all her limb muscles. On admission, we noted muscle weakness in her trunk and in her proximal limb muscles, although, her muscle MRI showed no remarkable findings. However, her serum CK level (2,747U/L) was above the normal range. Histopathological examination of muscle biopsy, performed from the left biceps brachii muscle, revealed immune-mediated necrotizing myopathy (IMNM). Her serum samples were negative for myositis-associated autoantibodies (MAAs), anti-SRP, and HMGCR antibodies. However, as the anti-SS-A antibody level in her serum was high (53.2U/mL), we conducted the salivary gland biopsy and the Schirmer test on her eyes. We found lymphocytes infiltration in her salivary gland tissue, and thus, she was diagnosed with primary Sjögren syndrome (SjS). We also observed necrotizing myopathy associated with the SjS. Following her treatment with oral steroids, her symptoms and CK level improved. Although, inflammatory myositis frequently occurs in association with general collagen diseases, necrotizing myopathy has rarely been observed secondary to SjS. We report here this rare case study along with the review of the relevant literature. (Received June 24, 2020; Accepted October 12, 2020; Published February 1, 2021).

Eosinophilic Granulomatosis with Polyangiitis Presenting with Myocarditis as an Initial Symptom: A Case Report and Review of the Literature.

A 66-year-old woman with a history of bronchial asthma had shortness of breath and fatigue upon mild exercise. She was diagnosed as congestive heart failure. A blood test showed eosinophilia without the presence of anti-neutrophil cytoplasmic antibody (ANCA), and a myocardial biopsy specimen revealed eosinophilic infiltration in the myocardium. Eosinophilia was improved when she was administered short-term methylprednisolone. After that, she had numbness and pain in her lower limbs with re-elevation of eosinophils. She had dysesthesia and hypalgesia in the distal part of the limbs. Sural nerve biopsy revealed axonal degeneration and thickness of the arterial wall, indicating a diagnosis of eosinophilic granulomatosis with polyangiitis (EGPA). Two courses of steroid pulse therapy were performed, resulting in marked improvement of her sensory symptoms. ANCA-negative EGPA might be associated with myocarditis and peripheral neuropathy. A sufficient immunotherapy should have been considered to prevent rapid progression.

Clinical features of Barré-Lièou syndrome and efficacy of trazodone for its treatment: A retrospective single center study.

Barré-Lièou syndrome (BLS) is a manifestation of various autonomic and secondary symptoms including muscle stiffness, tinnitus, dizziness, and pain in various body parts. Although considered to be caused by hyperactivation of the autonomic nervous system due to trauma, there is currently no firmly established etiology or evidence on the treatment and clinical features of BLS. We retrospectively examined the clinical features of BLS and evaluated the efficacy of trazodone (TZD) for its treatment. We conducted a retrospective analysis of the data of 20 consecutive cases with suspected BLS who were treated in our hospital between 2016 and 2019. BLS symptoms were rated on a 10-point scale, and two groups were defined, that is, a mild-BLS group (BLS scores, 1-5) and a severe-BLS group (BLS scores, 6-10). Univariate analysis of patient factors was performed. The BLS score was 6.0 ± 1.7, and the maximum TZD dose was 80 ± 34 mg/day; nine patients (45%) were TZD free, and no TZD side effects were observed, while all patients had a good clinical outcome. There were significant differences between the mild-BLS and severe-BLS groups in the period from injury to diagnosis (p = 0.015), chest/back pain (p < 0.001), constipation (p = 0.001), and maximum TZD dose (p = 0.008). BLS involves posttraumatic autonomic symptoms accompanied by depression and insomnia. The sympathetic hypersensitivity theory could explain its etiology. TZD could effectively and safely treat BLS, and early diagnosis and treatment can contribute toward good clinical outcomes. Enhanced recognition and understanding of this disease are warranted.

Types of intraparenchymal hematoma as a predictor after revascularization in patients with anterior circulation acute ischemic stroke.

BACKGROUND: Intracranial hemorrhage after revascularization for acute ischemic stroke is associated with poor outcomes. Few reports have examined the relationship between parenchymal hematoma after revascularization and clinical outcomes. This retrospective study aimed to investigate the risk factors and clinical outcomes of parenchymal hematoma after revascularization for acute ischemic stroke. METHODS: Ninety-three patients underwent revascularization for anterior circulation acute ischemic stroke. Patient characteristics and clinical outcomes were compared between patients with and without post procedural parenchymal hematoma using the following parameters: age, sex, occlusion location, presence of atrial fibrillation, diffusion-weighted imaging-Alberta stroke program early computed tomography score (DWI-ASPECTS), National Institute of Health Stroke Scale (NIHSS) score, recombinant tissue plasminogen activator, thrombolysis in cerebral infarction > 2b, door-to-puncture time, onset-to-recanalization time, number of passes, and modified Rankin Scale scores. RESULTS: Parenchymal hematomas were not significantly correlated with age, sex, occlusion location, atrial fibrillation, DWI-ASPECTS, NIHSS score, recombinant tissue plasminogen activator, thrombolysis in cerebral infarction > 2b, door-to-puncture time, onset-to-recanalization time, and number of passes, but were significantly correlated with poor clinical outcomes (P = 0.001) and absence of the anterior communicating artery evaluated using pre procedural time-of-flight magnetic resonance angiography (P = 0.03). CONCLUSION: Parenchymal hematoma was a predictor of poor outcomes. In particular, the absence of the anterior communicating artery on pre procedural time-of-flight magnetic resonance angiography is a potential risk factor for parenchymal hematoma after revascularization for anterior circulation acute ischemic stroke.

[A case of anti-aquaporin 4 antibody-positive Sjögren syndrome associated with a relapsed myelitis in pregnancy].

It is known that pregnancy influences the relapsing rate of multiple sclerosis (MS); however, interaction between pregnancy and relapse of neuromyelitis optica (NMO), a distinct disease from MS, remains unclear. A 34-year-old woman who 1 year previously had clinical history of Sjögren syndrome complicated by myelitis with the presence of anti-AQP4 antibody in her serum, although there was no optic neuritis involvement, was neurologically normal at time of becoming pregnant. In the 22nd week of her pregnancy, however, she developed abdominal belt-shaped numbness and sensory impairment followed by weakness of bilateral lower limb leading to difficulty of her gait. MR imaging revealed hyperintense lesions within the spinal cord extending from C2 to T2 vertebral level with marked spinal cord swelling, indicating relapse of myelitis associated with anti-AQP4 antibody. She was treated with intravenous corticosteroid with marked benefits for her neurological status; she was able to walk without assistance after the treatment. However, in the 30th week she relapsed with myelitis at T2 to T9 vertebral level on MR imaging. Intravenous steroid administration again elicited improvement. She delivered a baby via Caesarean section at 34 weeks of pregnancy. After delivery, she started taking oral corticosteroid as preventive therapy for further relapse of myelitis; thus far she has had no relapse at 7 months of follow-up. There are few reports regarding the influence of pregnancy on anti-AQP4 antibody-positive myelitis. Although further investigation should be done to clarify the difference of immunological changes during pregnancy between NMO and conventional MS, our case together with previous reports indicate increased risk of relapse during pregnancy in NMO. It is necessary to remain vigilant against possible risk of relapse during pregnancy in patients with NMO and/or positive anti-AQP4 antibody. Intravenous steroid administration seems safe and effective against relapse of NMO during pregnancy.

Isolated Cerebral Vasculitis in the Unilateral Middle Cerebral Artery in a Case with SLE.

A 47-year-old woman, who was diagnosed to have systemic lupus erythematosus (SLE), was admitted because she suffered a severe ischemic stroke three weeks after experiencing a transient attack of aphasia. Diffusion-weighted MRI revealed high intensity at the borderzone of the middle cerebral artery (MCA), while the proximal portion of the left MCA was occluded with its vascular wall enhanced by gadolinium. Intravenous methylprednisolone and heparin were administrated without any symptomatic benefit. She developed severe right hemiparesis with aphasia. Isolated cerebral vasculitis in the large vessel has been rarely reported in SLE patients. The presence of an enhanced vascular wall in the MRI with gadolinium could support the diagnosis.

Myasthenia Gravis with Anti-Muscle-Specific Tyrosine Kinase Antibody during Pregnancy and Risk of Neonatal Myasthenia Gravis: A Case Report and Review of the Literature.

A 31-year-old woman presented with a nasal voice, dysarthria, and upper limb weakness during her first pregnancy. Soon after delivery of her first baby, her symptoms disappeared. At the age of 34 years, during her second pregnancy, her nasal voice re-appeared. After delivery of the second baby, her nasal voice worsened, and bilateral eyelid ptosis and easy fatigability were also evident. She was referred to our hospital. Because of her myasthenic symptoms and anti-muscle-specific tyrosine kinase (MuSK) antibody (Ab)-positive status, she was diagnosed as having myasthenia gravis (MG). Her symptoms were worse than those in her first pregnancy. She was treated with oral steroid and double filtration plasmapheresis. After initiation of treatment, her myasthenic symptoms improved completely. In addition, her baby developed transient neonatal MG (TNMG) on the fourth day after birth and then gradually recovered over 30 days. It should be noted that symptoms of patients with anti-MuSK Ab-positive MG (MuSK-MG) can deteriorate during pregnancy, and the babies delivered of patients with MuSK-MG have a high probability of developing TNMG.

Juvenile Muscular Atrophy of the Proximal Upper Extremity as So-Called Proximal-Type Hirayama Disease: Case Report and Review of the Literature.

Hirayama disease is a distinct type of cervical myelopathy characterized by juvenile onset of unilateral muscular atrophy of a distal upper extremity. We report herein a case with Hirayama disease-like juvenile muscular atrophy involving proximal muscles in the upper extremities. In this case, in the flexion position of the neck, cervical magnetic resonance imaging revealed that the spinal cord was compressed by expansion of the posterior extradural space with forward displacement of the dura matter. These neuroimaging results are identical to those of Hirayama disease. However, the involved muscles in this case were the proximal muscles, unlike Hirayama disease. Five previous cases have displayed this rare subtype of Hirayama disease. The cause of the unique phenotype may be abnormal cervical column alignment, with upper cervical kyphosis producing a higher apex of the vertebral level in a cervical flexion position, resulting in mid-cervical segmental myelopathy.

Pituitary metastasis of breast cancer mimicking IgG4-related hypophysitis.

IgG4-related hypophysitis, which is the pituitary gland inflammation caused by IgG4 positive lymphocytes, can affect cavernous sinus and orbital apex leading to developing cranial nerve related symptoms such as orbital apex syndrome (OAS). Here we report a case of hypopituitarism associated with OAS caused by pituitary metastasis of the breast cancer with elevated serum IgG4 level, who initially resembled to IgG4-related hypophysitis. Although this case had some features in common with igG4-related hypophysitis. The symptoms and pituitary enlargement were typical. However, steroid treatment did not improve her symptoms. Thus, we performed a tissue biopsy. Histopathologic examination of the hypophyseal tumor confirmed metastatic breast cancer in her pituitary. Pituitary metastatic tumor should be suspected if a case with OAS was once diagnosed as a cancer.

Sensitivity and specificity of cardiac 123I-MIBG scintigraphy for diagnosis of early-phase Parkinson's disease.

INTRODUCTION: The purpose of this study was to investigate the diagnostic accuracy of cardiac 123I-metaiodobenzylguanidine (MIBG) scintigraphy for the diagnosis of Parkinson's disease (PD), especially in the early stages. METHODS: We investigated 600 patients who underwent cardiac 123I-MIBG scintigraphy to diagnose their parkinsonism and/or cognitive impairment. Of 600 research subjects, 272 patients were clinically diagnosed with PD. MIBG uptake was compared between patients with PD and other diseases. Furthermore, the sensitivity and specificity of cardiac 123I-MIBG scintigraphy to diagnose PD was estimated by disease duration (<3 years: early group vs. over 3 years: late group). We also assessed the relationship between MIBG uptake and Hoehn & Yahr stage. RESULTS: MIBG uptakes of PD patients were significantly decreased compared with those of other diseases except dementia with Lewy bodies and pure autonomic failure (p < .05 for all). In the early group, the sensitivity and specificity of the delayed heart to mediastinum (H/M) ratio were 68.7% and 91.7%, respectively, while in the late group, the sensitivity was 86.3% and the specificity was 74.0%. In addition, the early and delayed H/M ratios were decreased with higher Hoehn & Yahr stages in PD patients. CONCLUSION: Our findings demonstrated that cardiac 123I-MIBG scintigraphy had sufficient diagnostic accuracy to detect the early phase of PD. Indeed, this study of a large number of patients provides further external validation that MIBG has diagnostic ability to distinguish PD from atypical parkinsonism.